Explanation:
The above
computer animated picture depicts how a
very compact star would
look to a nearby observer. The star pictured is actually more compact that
any known except a
black hole, so it is only hypothetical. The observer is
situated at the photon sphere, where photons can orbit in a circle. To
help the viewer better visualize the great distortions created by gravity,
a map of the Earth was projected onto the star, and a map of the familiar
night sky was projected above. From here one can either look down and see
several duplicate images of the entire surface of the star, look up
and see several duplicate images of the entire night sky, or look along the
photon sphere and see the back of one's own head.